1. Field of the Invention
Embodiments of the present invention generally relate to a downhole seal arrangement. More particularly, embodiments of the present invention relate to seal stem arrangement for reconnecting with a tubular.
2. Description of the Related Art
During the life of a well, an operator may decide to reconnect to a liner. One method is to insert a tie back string having a seal stem at a lower end for establishing pressure integrity with a liner. FIG. 1 shows a seal stem disposed inside a polish bore receptacle 3 (“PBR”) of the liner. The seal stem includes a mandrel 10 and three assemblies 11, 12, 13 of Chevron-type seal rings disposed on a reduced diameter portion of the mandrel 10. Each assembly 11, 12, 13 includes upper and lower travel stops 14, 16 attached to the mandrel 10. Two stacks of oppositely facing Chevron-type seal rings 21, 23 are disposed between the travel stops 14, 16. As shown, a stack of upwardly oriented seal rings 21 and a stack of downwardly oriented seal rings 22 are disposed on each side of an o-ring 23. Each stack may include as many as twenty seal rings 21, 22 to provide adequate sealing with the PBR. The Chevron seal rings 21, 22 are oriented in opposite directions to seal against differential pressures in either direction.
One of the drawbacks of this design is a reduced diameter portion 8 is created to accommodate the seal assemblies 11, 12, 13. The reduced diameter portion 8 decreases the burst and collapse integrity of the mandrel 10. Another drawback is one or more of the seals may roll off the seal stem during insertion, removal, or circulation.
There is a need, therefore, for a seal arrangement that does not require a compromise of the integrity of the seal stem. There is also a need for a seal stem for reconnecting with a tubular without concerns of the seal rolling off the seal stem.